Angiographic methods for blood flow measurements

Radiopaque angiographic contrast agents are being used as indicators for the measurement of blood flow; the basic assumption for these measurements being that both blood and indicator flow nearly at the same rate. Indicators are injected into the circulation and recorded immediately by X-ray filming or video techniques; density changes at selected points along the recorded vessel are detected; dilution curves are plotted and blood flow is calculated graphically or by computer.